Acrylic Acid from Lactide and Process

ABSTRACT

Technical grade acrylic acid derived from renewable resources utilizing a homogeneous nickel catalyst system by a process including reacting lactide with acetic acid to form 2-acetoxypropionic acid in the presence of a homogeneous nickel catalyst, pyrolyzing, with or without a catalyst, the 2-acetoxypropionic acid to acrylic acid and acetic acid, condensing and collecting the pyrolysis products in the presence of polymerization inhibitor(s) and purfying the acrylic acid by distillation in the presence of polymerization inhibitor(s). Acrylic acid and methyl acrylate are produced from methyl 2-acetoxypropionate which comes from fermentation derived lactic acid. The disclosed process will produce a “green” (i.e. renewable resources derived) acrylic acid and methyl acrylate ester.

REFERENCE TO PENDING APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/403,873 filed on Sep. 23, 2010 entitled AcrylicAcid and Esters from Lactide and U.S. Provisional Patent ApplicationSerial Number 61458112 filed on Nov. 18, 2010 entitled Process for theProduction of Acrylic Acid from Pyrolysis Product of Methyl2-Acetoxyproprionate.

REFERENCE TO MICROFICHE APPENDIX

This application is not referenced in any microfiche appendix.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally directed toward a process to createacrylic acid and methyl acrylate esters. More specifically, the presentinvention is directed toward a process to create technical grade acrylicacid or/and methyl acrylate ester from renewable resources.

For purposes of this invention, the term green technical grade acrylicacid or green acrylic acid refers to technical grade acrylic acidderived from renewable resources.

2. Background

The acrylic acid market is measured by the production of crude acrylicacid. Crude acrylic acid (also known as technical grade acrylic acid) isnot an item of commerce. However, it is either further purified intoglacial acrylic acid or converted into Acrylate esters. The market isequally split between glacial and ester production (i.e. 50% of thecrude goes to glacial and 50% goes to esters). The worldwide capacityfor crude acrylic acid has been estimated at over 9 billion pounds peryear.

All current production of crude acrylic acid is via a two stage airoxidation of propylene. In the first stage propylene is oxidized toacrolein using an expensive Bi/Mo based mixed metal oxide catalyst. Inthe second stage the acrolein is oxidized to acrylic acid using anexpensive Bi/V based mixed metal oxide catalyst. Both oxidation stepsare conducted at high temperature (320° C. and 280° C., respectively) invery expensive shell and tube reactors using molten salt heat exchangefluids.

The hot gases exiting the second reactor are rapidly cooled and thenon-condensibles are separated from the condensed aqueous acrylic acidsolution in the absorber. The concentration of the acrylic acid in thisaqueous solution depends on the technology employed. One technology usessteam injection into the reactors to control flammability and the otheruses recycle gas injection instead of steam. Steam injection can lead toan aqueous acrylic acid solution as low as ˜20% while recycle gasinjection can produce an aqueous acrylic acid as high as 70% leaving theabsorber.

This aqueous acrylic acid is then subjected to a complicatedpurification system consisting of several towers to produce crudeacrylic acid (technical grade). In the first tower water is removed. Ifsteam was used as the diluent in the reactors the water is removed viaextraction and azeotropic distillation is used if recycle gas wasemployed. In both cases the dewatered acrylic acid is then subjected tomultiple vacuum distillations to remove both light and heavyby-products. The final product from these distillation steps istechnical grade acrylic acid (>99% purity).

The capital cost for a crude acrylic acid unit is very high.Furthermore, the high raw material cost of propylene make it vulnerableto a new technology for some of the future Acrylic acid productionunits.

Currently, there is no commercially viable micro-organism which candirectly produce acrylic acid via fermentation. However, there are knownmicro-organisms which can produce specific hydroxypropionic acids(acrylic acid precursors) via glucose fermentation. There are twoconfigurational isomers of hydroxypropionic acid. The alpha isomer iscommonly known as lactic acid and the beta isomer is better known a3-hydroxypropionic acid (3HPA). Lactic acid has been produced on acommercial scale via fermentation for over one hundred years while 3HPAis not yet commercially available.

Both isomers undergo acid catalyzed dehydration yielding acrylic acid,see Chemical Reaction 1 as illustrated in FIG. 1.

However, the two isomers yield different amounts of acrylic acid. Thebeta isomer (3HPA) dehydrates in near quantitative yields while thealpha isomer (lactic acid) only realizes ˜55% yield. These dehydrationefficiencies are essentially the same for both the free acids and thecorresponding lactate esters. The reason for this difference inselectivity to acrylic acid is most likely related to the location ofthe intermediate carbocation. Lactic acid proceeds through a carbocationalpha to the carbonyl (which can readily undergo decomposition) and 3HPAproceeds through a carbocation beta to the carbonyl (i.e. the positivecharge is removed from the carbonyl and can only readily eliminate aproton forming acrylic acid).

While the dehydration of lactic acid to acrylic acid has been studiedfor over 50 years, the yield remains poor. This poor dehydrationefficiency is also observed for lactate esters. However, it has beenshown that the acetylated product of lactic acid (2-acetoxypropionicacid) readily undergoes pyrolysis to acrylic acid in ˜95% yields, seeChemical Reaction 2 as illustrated in FIG. 2. High yields have also beenreported for the pyrolysis of methyl 2-acetoxypropionate.

This pyrolysis reaction is a cyclic elimination of acetic acid and goesin high yields because it does not proceed through the carbocationintermediate associated with the dehydration of lactic acid. Obviouslylactic acid could be converted into this acetoxy derivative and thenpyrolyzed to produce acrylic acid in high yields. The problem with thisroute is that the acetoxy derivative would be typically made by reactionof lactic acid with either acetic anhydride or ketene. The recoveredacetic acid could be converted back to anhydride or ketene using aketene furnace, but a ketene furnace is very expensive. Furthermore, thelactic acid is only available as an aqueous solution so excess ketene oranhydride would be consumed by the water present in the aqueous lacticacid further decreasing the economics of this route. To utilize thisroute via the acetoxy derivative one must be able to prepare it directlyfrom acetic acid.

Thus, there is a need for a more effective and efficient process tocreate acrylic acid and methyl acrylate ester.

BRIEF SUMMARY OF THE INVENTION

The present invention satisfies the needs discussed above. The presentinvention is generally directed toward a process to create acrylic acid.More specifically, the present invention is directed toward a process tocreate technical grade acrylic acid from renewable resources.

It is to be understood that the invention is not limited in itsapplication to the details of the construction and arrangement of partsillustrated in the accompanying drawings. The invention is capable ofother embodiments and of being practiced or carried out in a variety ofways. It is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and not oflimitation.

One aspect of the present invention discloses the use of a nickelcatalyst system with lactide (or other oligomers of lactic acid) andmethyl acetate to achieve high conversions of 2-acetoxypropionate. Afterthe contents are subjected to pyrolyzation, a mixture of methyl acrylateand acetic acid is obtained. This mixture can be transesterified to anequilibrium mixture of acrylic acid, acetic acid, methy acetate andmethy acrylate. After distillation, the resulting semi-purified acrylicacid would be a technical grade acrylic acid, and the methyl acetatereturns to the first reaction. The methyl acrylate and acetic acid canbe recycled to the transesterification of some of the methyl acrylatecan be taken as a product.

Upon reading the above description, various alternative embodiments willbecome obvious to those Skilled in the art. These embodiments are to beconsidered within the scope and spirit of the subject invention, whichis only to be limited by the claims which follow and their equivalents.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chemical representation of an isomer undergoing acidcatalyzed dehydration yielding acrylic acid.

FIG. 2 is a chemical representation of an acetylated product of lacticacid (2-acetoxypropionic acid) undergoing pyrolysis to acrylic acid.

FIG. 3 is a chemical representation of the opening of a lactide byreaction with acetic acid.

FIG. 4 is a chemical representation of the equilibration of a diacidwith a diester forming the monoester.

FIG. 5 is a chemical representation of a catalyst converting lactide andmethyl acetate into methyl 2-acetoxypropionate.

FIG. 6 is a chemical representation of a catalyst opening a lactide tothe acetoxy dimer of lactic acid.

FIG. 7 is a flow diagram of an embodiment of the transesterificationprocess of the present invention.

DESCRIPTION OF THE INVENTION

The present invention satisfies the needs discussed above. The presentinvention is generally directed toward a process to create acrylic acid.More specifically, the present invention is directed toward a process tocreate technical grade acrylic acid from renewable resources.

Green acrylic acid and acrylate products are prepared from fermentationderived lactic acid. Lactide (ananhydrous solid) is currently producedcommercially from aqueous lactic acid and used as the monomer for theproduction of polylactic acid. Accordingly, it is possible to open thelactide by reaction with acetic acid. See Chemical Reaction 3 asillustrated as FIG. 3.

This reaction is analogous to the known equilibration of a diacid with adiester forming the monoester, see Chemical Reaction 4 as illustrated asFIG. 4.

However, the simple equilibrium reaction suffer from low conversions. Acatalyst would need to be utilized to force the reaction to completion.The present invention discloses the use of a catalyst system prepared byplacing nickel acetate and nickel nitrate in acetic acid which shouldachieve high conversions of lactide to 2-acetoxypropionic acid at hightemperature (−250° C.). This nickel system is a good catalyst for theacid interchange reaction shown in Chemical Reaction 3. The samecatalyst has also been shown to convert lactide and methyl acetate (inthe presense of a small amount of acetic acid) into methyl2-acetoxypropionate, see Chemical Reaction 5 as illustrated in FIG. 5.

This same reaction can be applied to any relatively anhydrous oligomeror polymer of lactic acid. In other words, lactide (the cyclic dimer oflactic acid) is only one of several possible feeds for the envisionedprocess.

The catalyst for this reaction can be a mixture of any transition metalsalt of a strong inorganic acid and a transition metal salt of analiphatic carboxylic acid. Examples of preferred transition metals areiron, cobalt, nickel and manganese. Examples of preferred inorganic acidsalts are nitrate, chloride or perchlorate salts. The preferredcarboxylic acid salt is acetate but could be any carboxylic acid salt.In other words, the catalyst for this reaction is not limited to amixture of nickel nitrate and nickel acetate.

In one embodiment, at a low temperatures (˜115° C.) the catalyst opensthe lactide to the acetoxy dimer of lactic acid, see Chemical Reaction 6as illustrated in FIG. 6. In this case only one acid interchangereaction is occurring compared to the two acid interchange reactionsthat occur in Chemical Reaction 3. This acetoxy dimer of lactic acid canalso under the same pyrolysis reaction as acetoxypropionic acid but inthis case the reaction will yield one molecule of acetic acid and twomolecules of acrylic acid.

The acrylic acid unit of the present invention consists of a reactionstep in which lactide is reacted with acetic acid (both a reactant and asolvent for the reaction) in the presence of the nickel catalyst formingeither 2-acetoxypropionic acid or the acetoxy dimer. The2-acetoxypropionic acid (or acetoxy dimer) would then be pyrolyzed toacrylic acid and acetic acid. This pyrolysis can be done either with orwithout a catalyst. One possible catalyst for the pyrolysis step wouldbe calcium sulfate. Additional catalysts include zeolites such as USY,mordenite, H-ZSM-5, an X zeolite, beta zeolite, or Sn-beta zeolite;mesoporous molecular sieves such as MCM-41; naturally occurring acidicclays such as montmorillonite or kaolinite; an acidic metal oxide suchas alumina, tin (IV) oxide, molybdenum oxide; acidic non-metal oxidessuch as silica or phosphorous pentoxide; an acidic doped metal oxidesuch as sulfated zirconia, tungstated zirconia, sulfonated silica,tungstated tin oxide, W—Nb mixed-oxides; a Lewis acid such as FeCl3,AlCl3, ScCl3, or other transition metal salt of a mineral acid;hetero-poly acids such as tungstosilicic acid, molybdosilicic acid,tungstophosphoric acid, and molybdophosphoric acid; or a support dopedwith one of the foregoing classes of acidic catalysts and combinationsand mixtures thereof. All of the foregoing catalysts may be supported onstandard catalytic supports for catalysts such as a monolithic structure(as is commonly used in the automotive catalyst industry to support theexhaust catalysts), beaded or pelleted supports, and other structuredsupports like structured packings. The catalytic material may be used tomake the entire support structure, or the catalyst may be added to thesurface of an inert support structure by the standard techniques ofwashcoating or solution impregnation. Suitable inert supports for themonolithic structure or pellets or beads include cordierite, alumina,titania, zirconia, metals such as steel, silica, silicon carbide, boronnitride, silicon nitride, and other inert heat resistant materials.

The pyrolysis products would then be condensed and collected in areceiver. The contents of the receiver would be fed to a distillationtower where acetic acid and the crude acrylic acid would be separated.The crude acrylic acid would be sent to two towers for purification. Thefirst tower would remove light ends and the second tower Would removeheavy ends. The final product would be the overhead of the second tower.The recovered acetic acid would be recycled to the lactide reactionstep.

The distillation steps involving acrylic acid would be done in thepresence of polymerization inhibitors (e.g. phenothiazine, hydroquinone,p-methoxyphenol, 4-hydroxy TEMPO, etc.). The semi-purified acrylic acidfrom the distillation steps would be a technical grade acrylic acidwhich could be further purified to glacial acrylic acid by meltcrystallization or reacted with a C-1 to C-8 alcohol to produce anacrylate ester. The glacial acrylic acid product would be stabilized bythe addition of 200 ppm of MeHQ for commercial sales and the purifiedacrylate ester would be stabilized with 15 ppm of MeHQ.

As illustrated in FIG. 7, another embodiment of the present inventioninvolves a single transesterification reaction with minimal equipment.An oligomer of lactic acid is first converted into methyl2-acetoxypropionate by reaction with methyl acetate and then pyrolyzedto a mixture of acetic acid and methyl acrylate. The effluent from thispayrolysis reactor will be sent to a transesterification Reactor, with aresidence time of 30 minutes to 2 hours. The transesterification Reactorwill be warm (˜80 C.) and will have either a tranesterificationcatalyst. The transesterification catalyst can either be a liquid orsolid. Possible liquid catalysts would be mineral acids such as sulfuricacid or phosphoric acid. Other possible liquid catalyst would be organicsulfonic acids such as methane sulfonic acid or benzene sulfonic acid.Possible solid catalyst would be polymeric sulfonic acids like Amberlyst30 or Marathon C.

The Reactor is fed methyl acrylate and acetic acid. Transesterificationoccurs in this reactor. One possible version of this reactor is a fixedbed reactor where the tubes are filled with Amberlyst 30 resin. Givenenough time (about 30 minutes to 2 hours, depending temperature andcatalyst) the reaction will achieve an equilibrium distribution.

This transesterification reaction leads to a simplification of acrylicacid production by converting the methyl acrylate to the desired acrylicacid which is now ready for further refining and transesterifizingacetic acid to regenerate methyl acetate for use in the preparation ofmethyl 2-acetoxypropionate. This allows for methyl acetate to berecovered without azeotropes or other close boiling materials. Thus, thetransesterification is accomplished without the complications of water.

The methyl acetate would be recovered as the overhead stream of thefirst distillation tower after the transesterification reaction. Ifdesired the overhead could be a mixture of methyl acetate and methylacrylate which could then be separated in a subsequent distillationstep. In other words the methyl acetate is recycled to the process andmethyl acrylate is recovered for further refining and sales. The acrylicacid would be recovered for further purification as the bottom stream ofthe second distillation column. The overhead could be either pure aceticacid or a mixture of acetic acid and methyl acrylate that would be sentback to the transesterification reactor for recycle. In other words thepresent invention would allow the production of acrylic acid alone inone embodiment or both acrylic acid and methyl acrylate in anotherembodiment. This transesterification reaction could also be performedvia reactive distillation. The mixture of methyl acrylate and aceticeacid along with a liquid catalyst would be fed to the middle section ofa distillation tower while methyl acetate would be taken as thedistillate stream and acrylic acid as the residue stream from the tower.The liquid catalyst would be those previously mentioned. Alternatively,a solid acid catalyst could be incorporated in the tower packing.

While the invention has been described with a certain degree ofparticularity, it is manifest that many changes may be made in thedetails of construction and the arrangement of components withoutdeparting from the spirit and scope of this disclosure. It is understoodthat the invention is not limited to the embodiments set forth hereinfor purposes of exemplification.

The invention is demonstrated by but not limited by the followingexamples:

Example 1

A 250 mL round bottom flask was charged with 7.2 g of lactide, 60 g ofacetic acid, 0.2 g nickel acetate, 0.2 g of nickel nitrate and 0.1 g ofphenothiazine. The contents were refluxed for 6 hrs and then cooled toroom temperature and discharged. GC analysis indicated that the lactidehad been converted into the acetoxy dimer of lactic acid which is alsocalled 2-(2′-acetoxypropanoyloxy)propanoic acid.

Example 2

A 300 mL Parr autoclave was charged with 7.2 g of lactide, 100 g ofacetic acid, 0.5 g of nickel acetate, 0.5 g of nickel nitrate and 0.1 gof phenothiazine. The contents of the autoclave were heated and stirredat 250° C. and 300 psig for 4 hrs. The contents were then cooled to roomtemperature and discharged from the autoclave. GC analysis revealed thatthe lactide had been converted into 2-acetoxypropionic acid.

Example 3

A 300 mL Parr autoclave was charged with 7.2 g of lactide, 94 g ofmethyl acetate, 6 g of acetic acid, 0.5 g of nickel acetate, 0.5 g ofnickel nitrate and 0.1 g of phenothiazine. The contents of the autoclavewere heated and stirred at 225° C. and 500 psig for 4 hrs. The contentswere then cooled to room temperature and discharged from the autoclave.GC analysis revealed that the lactide had been mostly converted intomethyl 2-acetoxypropionate along with a small amount of2-acetoxypropionic acid.

Example 4

A 250 mL round bottom flask was charged with 43 g methyl acrylate, 30 gacetic acid, 5 g Purolite PD206 sulfonic acid resin, 0.03 g of 4-hydroxyTEMPO and 0.01 g nitrosobenzene. The flask was fitted with a refluxcondenser, a heating mantel and a magnetic stirrer. The contents wereheld at −85° C. for 6 hrs. At the end of the 6 hrs, GC analysis revealedthat the flask contained; 36.4% methyl acrylate, 25.4% acetic acid,17.5% methyl acetate and 19.3% acrylic acid.

1. A process for the production of technical grade acrylic acid whichconsists of: reacting lactide with acetic acid to form2-acetoxypropionic acid in the presence of a catalyst; pyrolyzing said2-acetoxypropionic acid to acrylic acid and acetic acid; condensing andcollecting said pyrolysis products in the presence of one or morepolymerization inhibitor; and purifying said acrylic acid bydistillation in the presence of said one or more polymerizationinhibitor.
 2. The process of claim 1 wherein said catalyst is defined asbeing a mixture of nickel acetate and nickel nitrate
 3. The process ofclaim 1 wherein said pyrolyzing said 2-acetoxypropionic acid isperformed with a catalyst.
 4. The process of claim 3 wherein saidcatalyst is calcium sulfate; a zeolite such as USY, mordenite, H-ZSM-5,an X zeolite, beta zeolite, or Sn-beta zeolite; mesoporous molecularsieves such as MCM-41; naturally occurring acidic clays such asmontmorillonite or kaolinite; an acidic metal oxide such as alumina, tin(IV) oxide, molybdenum oxide; acidic non-metal oxides such as silica orphosphorous pentoxide; an acidic doped metal oxide such as sulfatedzirconia, tungstated zirconia, sulfonated silica, tungstated tin oxide,W—Nb mixed-oxides; a Lewis acid such as FeCl₃, AlCl₃, ScCl₃, or othertransition metal salt of a mineral acid; hetero-poly acids such asTungstosilicic acid, Molybdosilicic acid, Tungstophosphoric acid, andMolybdophosphoric acid; or a support doped with one of the foregoingclasses of acidic catalysts and combinations and mixtures thereof. 5.The catalyst in claim 3 in which the active catalytic material is: a.Supported on a monolithic structure with a multiplicity of internalchannels for gas flow and surface reaction with the active catalyticmaterial washcoated on the internal surfaces of the monolith, b.Supported on a structured packing with the active catalytic materialsupported on the surface of the packing, c. Formed as a pelletedmaterial with at least the surface made of the catalytic material, d.Formed as a inert pelleted material supporting a surface of thecatalytic material, e. Supported on a monolithic or pelleted structureby solution impregnation.
 6. The process of claim 1 having the furtherstep of purifying said acrylic acid from step into glacial acrylic acidby melt crystallization.
 7. The process of claim 1 having the furtherstep of converting said acrylic acid into an acrylate ester by reactingsaid acrylic acid with a C-1 to C-8 alcohol.
 8. A process for theproduction of technical grade acrylic acid which consists of: reactinglactide with acetic acid to form acetoxy dimer in the presence of acatalyst; pyrolyzing said acetoxy dimer to acrylic acid and acetic acid;condensing and collecting said pyrolysis products in the presence of oneor more polymerization inhibitors; and purifying said acrylic acid bydistillation in the presence of said one or more polymerizationinhibitors.
 9. The process of claim 8 wherein said catalyst is definedas being a mixture of acetate and nitrate salts of nickel, cobalt, ironor manganese.
 10. The process of claim 8 wherein said pyrolyzing saidacetoxy dimer is performed with a catalyst.
 11. The process of claim 10wherein said catalyst is calcium sulfate; a zeolite such as USY,mordenite, H-ZSM-5, an X zeolite, beta zeolite, or Sn-beta zeolite;mesoporous molecular sieves such as MCM-41; naturally occurring acidicclays such as montmorillonite or kaolinite; an acidic metal oxide suchas alumina, tin (IV) oxide, molybdenum oxide; acidic non-metal oxidessuch as silica or phosphorous pentoxide; an acidic doped metal oxidesuch as sulfated zirconia, tungstated zirconia, sulfonated silica,tungstated tin oxide, W—Nb mixed-oxides; a Lewis acid such as FeCl₃,AlCl₃, ScCl₃, or other transition metal salt of a mineral acid;hetero-poly acids such as Tungstosilicic acid, Molybdosilicic acid,Tungstophosphoric acid, and Molybdophosphoric acid; or a support dopedwith one of the foregoing classes of acidic catalysts and combinationsand mixtures thereof.
 12. The catalyst in claim 10 in which the activecatalytic material is: a. Supported on a monolithic structure with amultiplicity of internal channels for gas flow and surface reaction withthe active catalytic material washcoated on the internal surfaces of themonolith, b. Supported on a structured packing with the active catalyticmaterial supported on the surface of the packing, c. Formed as apelleted material with at least the surface made of the catalyticmaterial, d. Formed as a inert pelleted material supporting a surface ofthe catalytic material, e. Supported on a monolithic or pelletedstructure by solution impregnation.
 13. The process of claim 8 havingthe further step of purifying said acrylic acid from step into glacialacrylic acid by melt crystallization
 14. The process of claim 8 havingthe further step of converting said acrylic acid into an acrylate esterby reacting said acrylic acid with a C-1 to C-8 alcohol.
 15. A processfor the production of acrylic acid which comprises the following steps:a) reacting methyl acetate with a lactic acid oligomer to produce methyl2-acetoxypropionate in the presence of a catalyst and acetic acid; b)pyrolyzing methyl 2-acetoxypropionate to methyl acrylate and aceticacid; c) transesterifying in a reactor the methyl acrylate and aceticacid to a mixture of methyl acrylate, acetic acid, methyl acetate andacrylic acid with a catalyst; d) separating the methyl acetate forrecycle to the methyl 2-acetoxypropionate reactor; e) separating theacrylic acid for further refining; and f) separating the mixture ofmethyl acrylate and acetic acid for recycle to the transesterificationreactor.
 16. The catalyst in claim 15 step A is a mixture of the acetateand nitrate salts of either nickel, cobalt, iron or manganese.
 17. Theprocess for the production of acrylic acid of claim 15 wherein thecatalyst set out in step C is a mineral acid.
 18. The process for theproduction of acrylic acid of claim 17 wherein the mineral acid issulfuric acid.
 19. The process for the production of acrylic acid ofclaim 17 wherein the mineral acid is phosphoric acid.
 20. The processfor the production of acrylic acid of claim 15 wherein the catalyst setout in step C is a solid acid.
 21. The process for the production ofacrylic acid of claim 20 wherein the catalyst is a strong acid resin.22. The process for the production of acrylic acid of claim 21 whereinthe strong acid resin is Amberlyst
 30. 23. The process for theproduction of acrylic acid of claim 21 wherein the strong acid resin isMarathon C.
 24. The process for the production of acrylic acid of claim15 wherein the catalyst set out in step C is an organic sulfonic acid.25. The process for the production of acrylic acid of claim 24 whereinthe organic sulfonic acid is methane sulfonic acid.
 26. The process forthe production of acrylic acid of claim 24 wherein the organic sulfonicacid is benzene sulfonic acid.
 27. The process for the production ofacrylic acid of claim 15 wherein the lactic acid oligomer is lactide.28. The process of claim 15 having the further step of purifying saidacrylic acid from step into glacial acrylic acid by meltcrystallization.
 29. The process of claim 15 having the further step ofconverting said acrylic acid into an acrylate ester by reacting saidacrylic acid with a C-1 to C-8 alcohol.
 30. A process for theco-production of acrylic acid and methyl acrylate which comprises thefollowing steps: a) reacting methyl acetate with a lactic acid oligomerin the presence of a catalyst and acetic acid to produce methyl2-acetoxypropionate; b) pyrolyzing methyl 2-acetoxypropionate to methylacrylate and acetic acid; c) transesterifying in a reactor the methylacrylate and acetic acid to a mixture of methyl acrylate, acetic acid,methyl acetate and acrylic acid with a catalyst; d) separating themethyl acetate for recycle to the methyl 2-acetoxypropionate reactor; e)separating acrylic acid for further refining; f) separating the methylacrylate for further refining; and g) separating acetic acid for recycleto the transesterification reactor.
 31. The catalyst in claim 30 Step Ais a mixture of the acetate and nitrate salts of either nickel, cobalt,iron or manganese
 32. The process for the co-production of acrylic acidand methyl acrylate of claim 30 wherein the catalyst set out in step Cis a mineral acid.
 33. The process for the co-production of acrylic acidand methyl acrylate of claim 32 wherein the mineral acid is sulfuricacid.
 34. The process for the co-production of acrylic acid and methylacrylate of claim 32 wherein the mineral acid is phosphoric acid. 35.The process for the co-production of acrylic acid and methyl acrylate ofclaim 30 wherein the lactic acid oligomer is lactide.
 36. The processfor the co-production of acrylic acid and methyl acrylate of claim 30wherein the catalyst of step C is a solid acid.
 37. The process for theco-production of acrylic acid and methyl acrylate of claim 30 whereinthe catalyst of step C is a strong acid resin.
 38. The process for theco-production of acrylic acid and methyl acrylate of claim 37 whereinthe strong acid resin is Amberlyst
 30. 39. The process for theco-production of acrylic acid and methyl acrylate of claim 37 whereinthe strong acid resin is Marathon C.
 40. The process for theco-production of acrylic acid and methyl acrylate of claim 30 whereinthe catalyst of step C is an organic sulfonic acid.
 41. The process forthe co-production of acrylic acid and methyl acrylate of claim 40wherein the organic sulfonic acid is benzene sulfonic acid.
 42. Theprocess for the co-production of acrylic acid and methyl acrylate ofclaim 40 wherein the organic sulfonic acid is methane sulfonic acid. 43.The process of claim 30 in which the catalyst in step (b) is calciumsulfate; a zeolite such as USY, mordenite, H-ZSM-5, an X zeolite, betazeolite, or Sn-beta zeolite; mesoporous molecular sieves such as MCM-41;naturally occurring acidic clays such as montmorillonite or kaolinite;an acidic metal oxide such as alumina, tin (IV) oxide, molybdenum oxide;acidic non-metal oxides such as silica or phosphorous pentoxide; anacidic doped metal oxide such as sulfated zirconia, tungstated zirconia,sulfonated silica, tungstated tin oxide, W—Nb mixed-oxides; a Lewis acidsuch as FeCl₃, AlCl₃, ScCl₃, or other transition metal salt of a mineralacid; hetero-poly acids such as Tungstosilicic acid, Molybdosilicicacid, Tungstophosphoric acid, and Molybdophosphoric acid; or a supportdoped with one of the foregoing classes of acidic catalysts andcombinations and mixtures thereof.
 44. The catalyst in claim 30 in whichthe active catalytic material is: a. Supported on a monolithic structurewith a multiplicity of internal channels for gas flow and surfacereaction with the active catalytic material washcoated on the internalsurfaces of the monolith, b. Supported on a structured packing with theactive catalytic material supported on the surface of the packing, c.Formed as a pelleted material with at least the surface made of thecatalytic material, d. Formed as a inert pelleted material supporting asurface of the catalytic material, e. Supported on a monolithic orpelleted structure by solution impregnation.
 45. A process for theproduction of technical grade acrylic acid which consists of: reactinglactide with methyl acetate to form methyl 2-acetoxypropionate in thepresence of a catalyst; pyrolyzing said methyl 2-acetoxypropionate tomethyl acrylate and acetic acid; condensing and collecting saidpyrolysis products in the presence of one or more polymerizationinhibitor; transesterifying the recovered mixture to an acrylic acidcontaining mixture and purifying resulting said acrylic acid mixture bydistillation in the presence of said one or more polymerizationinhibitor.
 46. The process of claim 45 wherein said catalyst is definedas being a mixture of acetate and nitrate salts of nickel, cobalt, ironor manganese.
 47. The process of claim 45 wherein said pyrolyzing saidmethyl 2-acetoxypropionate is performed with a catalyst.
 48. The processof claim 47 wherein said catalyst is calcium sulfate; a zeolite such asUSY, mordenite, H-ZSM-5, an X zeolite, beta zeolite, or Sn-beta zeolite;mesoporous molecular sieves such as MCM-41; naturally occurring acidicclays such as montmorillonite or kaolinite; an acidic metal oxide suchas alumina, tin (IV) oxide, molybdenum oxide; acidic non-metal oxidessuch as silica or phosphorous pentoxide; an acidic doped metal oxidesuch as sulfated zirconia, tungstated zirconia, sulfonated silica,tungstated tin oxide, W—Nb mixed-oxides; a Lewis acid such as FeCl₃,AlCl₃, ScCl₃, or other transition metal salt of a mineral acid;hetero-poly acids such as Tungstosilicic acid, Molybdosilicic acid,Tungstophosphoric acid, and Molybdophosphoric acid; or a support dopedwith one of the foregoing classes of acidic catalysts and combinationsand mixtures thereof.
 49. The catalyst in claim 47 in which the activecatalytic material is: a. Supported on a monolithic structure with amultiplicity of internal channels for gas flow and surface reaction withthe active catalytic material washcoated on the internal surfaces of themonolith, b. Supported on a structured packing with the active catalyticmaterial supported on the surface of the packing, c. Formed as apelleted material with at least the surface made of the catalyticmaterial, d. Formed as a inert pelleted material supporting a surface ofthe catalytic material, e. Supported on a monolithic or pelletedstructure by solution impregnation.
 50. The process of claim 45 havingthe further step of purifying said acrylic acid from step into glacialacrylic acid by melt crystallization.
 51. The process of claim 45 havingthe further step of converting said acrylic acid into an acrylate esterby reacting said acrylic acid with a C-1 to C-8 alcohol.
 52. Thetransesterification step of claim 15 step C is accomplished via reactivedistillation
 53. The transesterification step of claim 30 step C isaccomplished via reactive distillation
 54. The transesterification stepof claim 45 is accomplished via reactive distillation